In this study, the syntheses of oxygen‐free graphene sheets and the method of its fixation at an oil‐aqua interface were presented. The graphene sheets were prepared by exfoliation of synthetic graphite powder in an aqua‐organic medium under ultrasound irradiation. N,N‐Dimethyloctylamine‐ (DMOA‐) aqua emulsion was used as the liquid medium, and pH was equal to 3. The obtained graphene nanosuspension was fractionated by sedimentation and decanted according to the weight. The graphene nanoparticle fractions, differing in configuration and number of layers, have been characterized using transmission electron microscopy (TEM), electron diffraction, HRTEM, Raman spectroscopy, and electron energy loss spectroscopy (EELS). It was found that using a DMOA‐aqua mixture as the liquid medium in ultrasonic treatment of synthetic graphite leads to the formation of oxygen‐free 1‐2‐layer graphene sheets attached to the DMOA‐aqua interface. The proposed method differs from known ones by using a small amount of more environmentally friendly organic substances. It allows to obtain large quantities of oxygen‐free graphene, and finally unconverted graphite can be directed for reuse. The proposed method allows to obtain both 2D graphene sheets with micron linear dimensions and 3D packages with a high content of defects. Both these species are in demand in areas related to the development of new materials with unique electrophysical properties.

N,N-Dimethylformamide (DMF) is often used as a liquid medium for the exfoliation of graphene for further use in a wide range of fields of science and technology: biomedical research, the technology of materials for electronics, and polymer composites. However, the nature of the processes of exfoliation of graphene sheets from the surface of micron-sized graphite particles and the subsequent stabilization of its dispersion has hardly been studied. In this work, the stages of graphene suspension formation in DMF and its mixture with aqua molecules under the action of ultrasonic irradiation were investigated. Characterization of graphene suspensions was carried out using transmission electron microscopy (TEM), dynamic light scattering (DLS), FTIR spectroscopy, Raman spectroscopy, and UV-Vis spectroscopy. The presence of aqua in the colloid system leads to the predominant formation of 3D graphene sheets with larger linear dimensions than in pure DMF. The defectiveness of the basal plane of graphene sheets obtained by exfoliation in pure DMF is significantly lower than in a mixture with aqua, while the edge defectiveness in both cases is rather low. A comprehensive analysis of the spectral data and TEM results with electron diffraction shows that in both cases graphene in suspensions is multilayer. However, if in pure DMF the graphene suspension was formed in one stage and its layering did not exceed five, then in the presence of aqua the formation of the dispersed phase occurred in two stages. At the second stage, a partial association of the sheets from finer fraction increases the sizes of graphene sheets, i.e., the particles with higher surface energy were attached to larger ones or associated with each other. Perhaps this is because aqua molecules included in the complexes and removed from the global hydrogen bond system, tend to restore these bonds and, thus, facilitate the fusion of the smallest and lightest graphene sheets.

The use of a nanostructured graphene-zirconia composite will allow the development of new materials with improved performance properties and a high functionality. This work covers a stepwise study related to the creation of a nanostructured composite based on ZrO₂ and graphene. A composite was prepared using two suspensions: nano-zirconia obtained by sol-gel synthesis and oxygen-free graphene obtained sonochemically. The morphology of oxygen-free graphene sheets, phase composition and the morphology of a zirconia powder, and the morphology of the synthesized composite were studied. The effect of the graphene sheets on the rheological and sintering properties of a nanostructured zirconia-based composite powder has been studied. It has been found that graphene sheets in a hybrid nanostructure make it difficult to press at the elastic deformation stage, and the composite passes into the plastic region at a lower pressure than a single nano-zirconia. A sintering mechanism was proposed for a composite with a graphene content of 0.635 wt%, in which graphene is an important factor affecting the process mechanism. It has been determined that the activation energy of the composite sintering is more than two times higher than for a single nano-zirconia. Apparently, due to the van der Waals interaction, the graphene sheets partially stabilize the zirconia and prevent the disordering of the surface monolayers of its nanocrystals and premelting prior to the sintering. This leads to an increase in the activation energy of the composite sintering, and its sintering occurs, according to a mixed mechanism, in which the grain boundary diffusion predominates, in contrast to the single nano-zirconia sintering, which occurs through a viscous flow.

Nanostructured composite particles of nano- and submicron sizes were synthesized by a combination of sol–gel and sonochemical techniques.

The laboratory technology was developed for the obtaining of nano and submicron powders of II-VIII group metal oxide as well as composites based on mesoporous metal silicates, metal oxides or nanoscale colloidal silver. The optimal parameters of the nanoparticles synthesis: a qualitative and quantitative composition of the reaction mass and thermal treatment mode were determined. The developed approach allows to carry out synthesis of nano sized metal oxide particles with a reference size, to vary it in the range 10–130 nm with an accuracy of 20–30 nm. A distinctive feature of our method is environmental friendliness, efficiency, and simplicity of the technological realization.